1. Field of the Invention
The present invention relates to a process for production of styrene polymers, and more particularly to a process for efficiently producing styrene polymers having such a stereo structure that side chains are mainly in the syndiotactic configuration.
2. Description of the Related Art
Polymers of vinyl compounds having substituent groups can be divided into three groups depending on the configuration of substituent groups, i.e., side chains of the polymers: isotactic, syndiotactic and atactic. Many of such vinyl polymers which have been heretofore been produced are isotactic or atactic.
Most of styrene polymers which have heretofore been produced are atactic although when usual radical polymerization initiators are used, there can be obtained styrene polymers having a stereo structure that is somewhat rich in the syndiotactic configuration. It is also known that when Ziegler type catalysts are used, there can be obtained styrene polymers having an isotactic structure.
However a method whereby styrene polymers of high syndiotactic configuration can be produced efficiently has not been known.
The present inventors have succeeded in developing a process for efficiently producing styrene polymers having a stereo structure that side chains are mainly in the syndiotactic configuration (see Japanese Patent Application Laid-Open No. 104818/1987).
In accordance with the above process, there can be obtained styrene polymers having a stereo structure that side chains are mainly in the syndiotactic configuration, but the molecular weight of the styrene polymers is difficult to control even if operations such as controlling the polymerization temperature are applied.